1. Field of the Disclosure
This disclosure relates generally to stackable riser components for use in providing access to septic tanks and other on-site waste treatment or drainage systems and, more particularly, to adapters for use in providing an interface between, for example, a lowermost stackable riser component and a lid of a septic tank, other on-site waste treatment system, or drainage system, such as a lid made of concrete or similar material.
2. Description of the Prior Art
Stackable riser components have been used to facilitate access to septic tanks and other on-site waste systems, as well as to drainage systems. These tanks and other waste or drainage systems are usually buried underground, and the stackable riser components are used to form a passageway, typically extending from above an opening in a lid of the tank, up to a higher elevation, at or near grade level. In an effort to ensure a secure interface between a stack, or column, of riser components and a lid of a septic tank, waste system, or drainage system, a recommended practice is to cast a lowermost riser component directly in place into the lid, which lid is typically made of concrete.
Those of ordinary skill in the art will understand that the term “concrete lid” or “lid” of the septic tank refers to the large, horizontally-oriented concrete slab, typically on the order of 4 feet by 8 feet, for example, provided at the top of the septic tank having a capacity from about 750 to about 1,250 gallons, and supported by the walls of the septic tank, as opposed to the term “concrete cover” or “cover,” which as used herein refers to the movable, generally smaller (and typically round) cover member conventionally associated with an opening in the concrete lid and used to gain access to the interior of the septic tank.
By only following the recommended practice of casting a lowermost stackable riser component directly in place into a concrete lid, there is a predicament when one desires to securely interface a stack of riser components over a tank, sewage waste system, or drainage system having an already-cast concrete lid. As an alternative, there have been attempts at adapters that are intended to adhere to the top of the already-cast concrete lid. For example, Zabel Environmental Technology of Crestwood, Ky. offers adapters (as part of its Zeus™ Access System), such as the 20″ tank adapter top, Model #RB-TA-T-20x2, for use in retrofitting existing concrete tank lids. The square-based adapter, shown in cross-section in FIG. 1 of U.S. Pat. No. 6,047,724, has a bottom edge, and is intended to be secured to the concrete lid by applying mastic adhesive to the bottom edge of the adapter top, and pressed onto the top of the concrete lid. That particular prior art adapter is also provided with circumferentially-mounted lugs, intended to pass through slots provided in an inwardly extending flange of a downwardly extending skirt portion of a bottom portion of a lowermost riser of a column, or stack, of risers. Upon rotation of the lowermost riser, the lugs engage inclined stop portions provided in the flange of the lowermost riser, to thereby prevent rotation of that lowermost riser, and thus rotation of a stack of risers, relative to the adapter.
Another adapter intended for installation on previously cast concrete tank lids is the riser adapter ring of Polylok Inc. of Yalesville, Conn. That riser adapter ring is currently available in a single size, having the capacity to fit both 20″ and 24″ diameter risers. A raised inner wall supports a 20″ diameter riser, with vertical ribs positioned on an inside surface of the inner wall. Some of the vertical ribs are provided with screw bosses, which are positioned to align with screw-receiving holes in the interior of a complementary 20″ or 24″ diameter riser. Screws are used to secure the lowermost riser of a column of risers to the riser adapter ring.
The interior location of the screw bosses in the Polylok adapter ring exposes unprotected portions of the securement screws at the intersection of the adapter ring and lowermost riser to corrosive gases within the column of risers. It would therefore be desirable to position screw bosses on the exterior of an adapter ring, rather than on the interior, so as to better isolate securement screws from corrosive gases within a column of risers leading up from the adapter ring located on the lid of a septic tank.